Shell Programming and Scripting

hey i was messing around a bit ... made me wonder...
If the error_correction.txt file had 3 columns,:

VenoM,Venom,Antivenom
nos,NOS,N2O
..
.
.
.


Now Suppose i have an if statement and depending on it i have to choose a value from column 2 or column 3, to replace the value in the main datafile.
How do i do this?

Code:

NR==FNR{a[$1]=(your condition to choose $2) ? $2 : $3;next}

i have around 4 conditions to check!
is it possible to redirect it to a subroutine? Or is it possible to use a something like a switch case?

Im doing something like this:
{
x=substr($1,2,5);
}
if ( x == "JB007" )
{
#Assign the value from the 3rd column of the error_correction file
}
else
{
#Assign the value from the 2nd column of the error_correction file
}

create a function that would return a binary value - check the returned value as in above.
Or better yet, just create a function that will return either $2 or $3, return this value - you'll do the array assignment of the return value.

cool thanks man

hope im not bugging you too much......
but hey another twist to this

what if i had:
VenoM,Venom,am1
Venom,VENOM,ax2
nos,NOS,ba1
nos,N2O,gd2
nos,n2o,as3
..
.
.
.

In this case, how do i pick out the value in the second column after matching 2 variables ie the 1st and the 3rd column to my main data file [assuming that the 3rd column is present in the 3rd field of the data file]

Sorry, don't follow you.
Could you give a better description.
Also, start using code tags when posting code/data samples - you'll improve the chances of your questions being looked at/answered.

My data file looks like this:
vgr,bugatti veron,,3.5,Venom,6,.......,....
vgr,lamborgini,,3.5,nos,6,.......,....
abc,bugatti veron,,3.5,Venom,6,.......,.......
.
.
.
.

What happens when there are multiple occurrences of the value to be replaced in my error correction file

Like nos appears twice but all we are doing is:

Code:

($4 in a)

This only matches the first occurrence.......
how do we make this a loop?